1. Field of the Invention
This invention relates to strip, backed, label media and, more particularly, to a gapless label media comprising a strip of media having a plurality of labels with leading and trailing edges abutting one another, the plurality of labels comprising a plurality of sequences of equal numbers of the labels with a first label of each sequence of the labels having a leading edge which is sensible. The invention also relates to methods and apparatus for printing on and applying labels which are staggered laterally across a media width.
2. Description of Related Art
In the prior art, labels 10 for printing on by one-at-a-time demand printers often come releasibly attached to a backing strip 12 as shown in FIG. 1. The backing strip 12 is moved from a supply roll (not shown) to the printhead 14 by a drive system 16 under the control of position and print logic 18. The labels 10 are positioned along a line running down the backing strip 12 so as to be equally laterally positioned under the printhead 14. There is also an equal gap 20 between the labels 10. The drive system 16 includes a stepping motor (not shown) which moves the backing strip 12 along at a constant rate. A sensor 22 connected to the position and print logic 18 senses the leading edge 24 of each label 10 at a known distance from the printhead 14. From the time the leading edge 24 is sensed, the position and print logic 18 counts the pulses of the stepping motor until it knows that the label 10 is positioned under the printhead 14 for printing. At that point, the position and print logic 18 starts printing the label with the printhead 14. With the gaps 20 between the labels 10, the sensor 22 can sense the leading edge 24 by the changes in light transmission between the backing strip 12 alone and the backing strip 12 in combination with the label 10; or, the difference in thickness or height that occurs at the leading edge 24 can be physically sensed. In the alternative, a hole 26 can be provided in the backing strip 12 in a known relationship to the leading edge 24.
In a so-called "gapless" label media 28 as depicted in FIG. 2, the labels 10 follow one behind the other on the backing strip 12 and there is no gap 20 to allow sensing of the leading edge 24. That is, the leading edge 24 of one label 10 is in the same position as the trailing edge 25 of the label 10 directly preceding it. The only prior art sensing approach available is the hole 26 in the backing strip 12. More recent developments in label technology can make the hole-in-the-backing-strip approach unusable. For example, in so-called "linerless" media, there is no backing strip. The labels 10 are continuous and are severed one from another after printing (or possibly before). In the case of pre-printed labels having standard sender information pre-printed thereon, there is a de facto "leading edge" that must be repeatably positioned under the printhead 14.
With the advent of printer dot resolutions on the order of 300 dots per inch (dpi) and higher, smaller printing is possible. Since it is desirable to put small labels on small electronic components and the like, there has been a simultaneous trend towards printing smaller labels. With small labels in particular, but with all labels in general, the provision of the gaps 20 adds to the manufacturing costs and wastes materials.
Wherefore, it is an object of this invention to provide a gapless label media which is sensible as to the position of leading edges of the individual labels thereof.
It is another object of this invention to provide a gapless label media which is sensible as to the position of leading edges of the individual labels thereof even in a linerless form.
It is still another object of this invention to provide methods and apparatus for positioning and printing on a gapless label media wherein the position of leading edges of the individual labels thereof is not sensible at every label position.
It is yet another object of this invention to provide methods and apparatus for positioning and printing on a gapless label media wherein the lateral position of the individual labels thereof is not consistent.
It is a further object of this invention to provide methods and apparatus for printing on a staggered label media and thereafter properly applying the printed labels to a desired position on an object.
Other objects and benefits of this invention will become apparent from the description which follows hereinafter when read in conjunction with the drawing figures which accompany it.